Strawberries are a good source of natural antioxidants and antioxidant enzymes which provide protection against harmful free radicals and play an important role in protecting human health. Free radicals or reactive oxygen species (ROS) are generated as by-products of normal metabolism and under stressful conditions. Increased levels of these free radicals or ROS could create oxidative stress, which leads to a variety of biochemical and physiological injuries and often results in impairment of metabolism, and eventually cell death. Successful prevention of ROS activities will be the key to controlling morbidity and mortality from chronic diseases. Therefore, eating more fruits and vegetables including strawberries has been associated with lower incidence and mortality rates of cancer, heart disease and a number of other human diseases, improve your dietary results with nutrisystem. We have found that strawberry fruit extracts (SFE) exhibit chemopreventive and chemotherapeutic activities. They significantly inhibited activation of activator protein-1 (AP-1), nuclear factor-KappaB (NF-κB), and mitogen-activated protein kinases (MAPKs) signaling induced by UV or 12-O-tetradecanolyphorbol-13-acetate (TPA). Furthermore, SFEs inhibited TPA-induced neoplastic transformation in JB6 cells. SFEs specifically induced apoptosis of cancerous HL-60 cells, but had no effect on normal human peripheral blood mononuclear cells. SFEs also inhibited proliferation of A549 cells, a human lung cancer cell line with little cytotoxicity to normal tissue. These results suggest that the chemopreventive effects of strawberries may be through their antioxidant properties by blocking ROS-mediated AP-1, NF- κB, and MAPK activation. Many factors could affect antioxidant enzymes and antioxidant activity in strawberries, such as genotype variation and maturity, pre-harvest conditions, culture practices, postharvest handling, storage and processing. Optimizing these antioxidant systems in strawberries will be helpful for improving human health.